Frequencies for first 10,000 rows of uab_venl30 variable in natl2005 dataset :

   Assisted |
Ventilation |
 < 30 min U |      Freq.     Percent        Cum.
------------+-----------------------------------
          1 |        433        4.33        4.33
          2 |      9,438       94.38       98.71
          9 |        129        1.29      100.00
------------+-----------------------------------
      Total |     10,000      100.00

by Jean Roth , jroth@nber.org , 22 Dec 2015